Electric Power Research Institute, EPRI Product ID: 3002011440, 2017

A biopolymer-enhanced centrifuge-dewatering process was investigated for remediating manufactured gas plant (MGP) sites in a pilot study of contaminated sediment from the Hudson River in Kingston, New York. The objective of the pilot was to apply commercially available dewatering equipment and assess issues related to scalability. Material handling tests were conducted with a desander and centrifuge at centrifuge feed rates of up to 100 gal/min, with and without biopolymer. The percentage of solids in the feed slurry ranged from 3-33%. Although control (water) trials failed immediately due to the stickiness of fines and hydrocarbons to metal surfaces, rendering impellers and submersible pumps ineffective, biopolymer addition eliminated hydrocarbon/fines agglomeration such that slurry transport of up to 33% solids was efficient and practical. A polyacrylamide surfactant in the decanter centrifuge separated the fines/hydrocarbons from process water based on density. Optimization of centrifuge variables produced reusable biopolymer process water and stackable cake that passed the TCLP test for clean discharge water and a wetter cake. The dewatering system processed 18% solids in the centrifuge feed at 100 gal/min for 20 min (2000 gal of slurry). At the conclusion of the pilot, centrifuge operating parameters were set to obtain clean water, which met discharge water quality requirements. An economic assessment of on-site processing costs showed 48% savings compared to mechanical excavation and gravity dewatering typical of MGP sediment remediation.